Many types of plastic tubes such as medical tubes and catheters are provided with one or more auxiliary lumens. For example, some suction catheters for draining or irrigating body cavities have an integral connector at the proximal end for connecting the main lumen with a suction force, and a distal end having openings extending through the tube side wall for communicating with body cavity fluids. An auxiliary lumen extending longitudinally within the side wall of the tube may be used to supply gas, such as air, or a liquid, such as an irrigation liquid, to the distal end of the main lumen or body cavity. Auxiliary lumens are also used in catheters to convey x-ray opaque liquid to a body cavity during fluroscopy. Also, metal rods can be disposed in an auxiliary lumen so that the catheter can be bent or formed into a desired permanent configuration such as to facilitate insertion of the catheter into a body cavity.
Plastic tubes with auxiliary lumens are conventionally made by extruding thermoplastic material through a suitable forming die to produce tubing with an auxiliary lumen. The extrudate is severed at selected points to provide a tube of desired length. One end portion of the tube may serve as an integral connector for coupling the tube with another device, such as a source of vacuum or other fluid system. The tubing extrudate may be produced with an enlargement or tapering "bubble" which, when cut through to form the tube, provides a conical or tapering integral tube connector. A rigid fluid connector or coupling element may be inserted into or over the tube connector (depending on the type) and rotated a limited amount into tight frictional engagement with the tube connector.
A serious drawback in the use of such tubes, especially when employed as medical tubes or catheters, is that a fluid leak sometimes occurs between the mating surfaces of the integral tube connector and the coupling element in an area adjacent the auxiliary lumen. Such fluid leaks occur because the wall of the tube connector adjacent the auxiliary lumen is generally thinner and more flexible than the other portions of the tube connector. Thus, sometimes fluid leaks from the main lumen at the connection of the tube and coupling element.
Auxiliary lumens can be closed after the extrudate has been cut into tubes or desired lengths by inserting filling material into the lumens. However, such a method generally increases the labor time and cost.